Interspinous implants with deployable wing

ABSTRACT

The present invention provides spinous process implants and associated methods. In one aspect of the invention, the implant includes at least one extension with a superior lobe pivotally connected to an inferior lobe, such as by a hinge, to allow unfolding of the at least one extension from a folded position to an unfolded position. In certain aspects, the folding extension may include fasteners to facilitate engagement with the spinous processes to provide both a flexion stop as well as an extension stop. The fasteners may have corresponding bores to allow the fasteners to reside in the bores to provide a compact profile for implantation. In another aspect of the invention, the implant is introduced to the surgical site using a lateral or paramedian approach and associated tools to facilitate the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.11/934,604, filed Nov. 2, 2007, now U.S. Pat. No. 8,241,330, titledSpinous Process Implants and Associated Methods; U.S. patent applicationSer. No. 12/020,282, filed Jan. 25, 2008, titled Spinal Implants andMethods; U.S. patent application Ser. No. 12/751,856, filed Mar. 31,2010, titled Spinous Process Implants and Associated Methods; U.S.patent application Ser. No. 12/538,710, filed Aug. 10, 2009, now U.S.Pat. No. 8,382,801, titled Spinous Process Implants, Instruments, andMethods; and U.S. patent application Ser. No. 12/854,125, filed Aug. 10,2010, titled Interspinous Implants and Methods, all of which areincorporated herein by reference as if set out in full.

FIELD

The present disclosure relates to interspinous implants that facilitatedistraction and fusion of a spine and, more particularly, to aninterspinous implant that may be easier to implant percutaneously.

BACKGROUND

The vertebrae of the human spine are arranged in a column with onevertebra on top of the next. An intervertebral disc lies betweenadjacent vertebrae to transmit force between the adjacent vertebrae andprovide a cushion between them. The discs allow the spine to flex andtwist. With age or injury, spinal discs begin to break down, ordegenerate, resulting in the loss of fluid in the discs, andconsequently, the discs become less flexible. Likewise, the discs becomethinner allowing the vertebrae to move closer together. Degenerationalso may result in tears or cracks in the outer layer, or annulus, ofthe disc. The disc may begin to bulge outwardly. In more severe cases,the inner material of the disc, or nucleus, may actually extrude out ofthe disc. In addition to degenerative changes in the disc, the spine mayundergo changes due to trauma from automobile accidents, falls, heavylifting, and other activities. Furthermore, in a process known as spinalstenosis, the spinal canal narrows due to excessive bone growth,thickening of tissue in the canal (such as ligament), or both. In all ofthese conditions, the spaces through which the spinal cord and thespinal nerve roots pass may become narrowed leading to pressure on thenerve tissue which can cause pain, numbness, weakness, or even paralysisin various parts of the body. Finally, the facet joints between adjacentvertebrae may degenerate and cause localized and/or radiating pain. Allof the above conditions, as well as others not specifically mentioned,are collectively referred to herein as spine disease.

Conventionally, surgeons treat spine disease by attempting to restorethe normal spacing between adjacent vertebrae. This may be sufficient torelieve pressure from affected nerve tissue. However, it is oftennecessary to surgically remove disc material, bone, or other tissuesthat impinge on the nerve tissue and/or to debride the facet joints.Most often, the restoration of vertebral spacing is accomplished byinserting a rigid spacer made of bone, metal, or plastic into the discspace between the adjacent vertebrae and allowing the vertebrae to growtogether, or fuse, into a single piece of bone. The vertebrae aretypically stabilized during this fusion process with the use of boneplates and/or pedicle screws fastened to the adjacent vertebrae.

Although techniques for placing intervertebral spacers, plates, andpedicle screw fixation systems have become less invasive in recentyears, they still require the placement of hardware deep within thesurgical site adjacent to the spine. Recovery from such surgery canrequire several days of hospitalization and long, slow rehabilitation tonormal activity levels.

Rather than spinal fusion, investigators have promoted the use of motionpreservation implants and techniques in which adjacent vertebrae arepermitted to move relative to one another. One such implant that has metwith only limited success is the artificial disc implant. The artificialdisc typically includes either a flexible material or a two-piecearticulating joint inserted in the disc space. Another such implant isthe spinous process spacer which is inserted between the posteriorlyextending spinous processes of adjacent vertebrae to act as an extensionstop and to maintain a minimum spacing between the spinous processeswhen the spine is in extension. The spinous process spacer allows theadjacent spinous processes to move apart as the spine is flexed. Theextension stop spacers, however, also have had limited success.

Recently, the trend has been back towards fusion devices rather thanmotion preservation devices. One promising recent implant is a spinalprocess fusion plate. Similar to the fusion implants, the spinal processfusion plate promotes fusion between adjacent vertebrae to relievepressure on the nerve. However, unlike more conventional spinal implantsystems, the spinal process fusion plate facilitates less invasiveprocedures than conventional spinal fusion surgery. The need stillexists for improved spinal process fusion plates to facilitate even lessinvasive surgery including, minimally invasive surgery, percutaneousimplantation, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

Various examples of the technology of the present application will bediscussed with reference to the appended drawings. These drawings depictonly illustrative examples of the technology described more fully hereinand are not to be considered limiting of its scope.

FIG. 1 is a posterior cross sectional view of an implant in situ that isdeployed using a tool consistent with the technology of the presentapplication;

FIG. 2 is a side elevational view of the implant of FIG. 1 in situ;

FIG. 3 is an exploded perspective view of the implant of FIG. 1;

FIG. 4 is a posterior elevational view of the implant of FIG. 1;

FIG. 5 is an anterior elevational view of the implant of FIG. 1;

FIG. 6 is a top plan view of the implant of FIG. 1;

FIG. 7 is a posterior elevational view of the implant of FIG. 1 showingthe assembly in an alternate position;

FIG. 8 is a side elevational view of the implant of FIG. 1;

FIG. 9 is a perspective view of a pair of implants like that of FIG. 1in situ;

FIG. 10 is a perspective view of an implant that is consistent with thetechnology of the present application;

FIG. 11 is a perspective view of a portion of the implant of FIG. 10 inan unfolded configuration;

FIG. 12 is a perspective view of a portion of the implant of FIG. 10 ina folded configuration:

FIG. 13 is a perspective view of a portion of the implant of FIG. 10 ina partially unfolded configuration;

FIG. 14 is a view of surgical access to surgically implant the implantof FIG. 10;

FIG. 15 is a perspective view of an implant that is consistent with thetechnology of the present application in a folded configuration;

FIG. 16 is a perspective view of the implant of FIG. 15 in an unfoldedconfiguration;

FIG. 17 is a perspective view of the implant of FIG. 15 with a portionof the implant transparent;

FIGS. 18-21 provide a perspective view of a method of implanting animplant consistent with the technology of the present application.

DESCRIPTION OF THE ILLUSTRATIVE EXAMPLES

The technology of the present application will be described in thecontext of spinal surgery, but one of ordinary skill in the art willrecognize on reading the disclosure that the technology may beapplicable to other medical fields. Moreover, the technology of thepresent application will be described with reference to certainexemplary embodiments. The word “exemplary” is used herein to mean“serving as an example, instance, or illustration.” Any embodimentdescribed herein whether or not specifically identified as “exemplary”is not to be construed as preferred or advantageous over otherembodiments. Further, the instrument(s) described in accordance with thetechnology of the present application facilitate surgical implantationof spinal process fusion plates. With that in mind, exemplary spinousprocess implants, according to the technology, may include a spacer andan extension extending outwardly from the spacer. The extension, whichmay be referred to as a wing, is sometimes described as being one ormore lobes associated with the spacer. The spinous process implant maybe configured for insertion between adjacent spinous processes of thecervical, thoracic, and/or lumbar spine. The spacer may be provided in avariety of sizes to accommodate anatomical variation amongst patientsand varying degrees of space correction. The spacer and extensions mayinclude openings to facilitate tissue in-growth to anchor the spacer tothe vertebral bodies such as tissue in-growth from the spinousprocesses. The spacer may be configured for tissue in-growth fromsuperior and inferior spinous processes to cause fusion of the adjacentspinous processes. The openings may be relatively large and/orcommunicate to a hollow interior of the spacer. A hollow interior may beconfigured to receive bone growth promoting substances such as bypacking the substances into the hollow interior. The openings may berelatively small and/or comprise pores or interconnecting pores over atleast a portion of the spacer surface. The openings may be filled withbone growth promoting substances.

The extension may extend transversely from the spacer relative to aspacer longitudinal axis to maintain the spacer between adjacent spinousprocesses. The extension may be described as foldable, extendable,deployable or the like from a flat configuration to facilitate minimallyinvasive implantation to an extended position to facilitate fusion. Asingle extension may extend in one or more directions or multipleextensions may be provided that extend in multiple directions. One ormore extensions may be adjustable longitudinally relative to one anotherand/or the spacer to allow the extensions to be positioned laterallyrelative to the spinous processes. A moveable extension may be providedthat is moveable axially relative to the spacer and another extension.Alternatively, a plurality of moveable extensions may be provided. Forexample, the extensions may clamp against the sides of the spinousprocesses to immobilize the spinous processes relative to one anotherand promote fusion between the adjacent vertebrae. The extensions mayinclude fasteners engageable with the spinous processes. The fastenersmay include sutures, wires, pins, straps, clamps, spikes, screws, teeth,adhesives, and/or other suitable fasteners. The fasteners may beintegrated into the extensions or they may be modular. Modular fastenersmay be adjustable, replaceable, and/or removable to allow tailoring ofthe kind and quality of fixation from rigid fixation to no fixation. Thespacer, extensions, and/or fasteners may advantageously be made ofdifferent materials. For example, the spacer and extensions may be madeof a relatively softer material while the fasteners may be made of arelatively harder material. For example, the spacer and/or extension maybe made of a polymer and/or other relatively soft material and thefastener may be made of a metal and/or other relatively hard material.

Insertion of spinous process implants may be facilitated by a set ofinstruments alternately engageable with one another to increase theinterspinous space and engageable with a spinous process implant to helpmaneuver it between adjacent spinous processes as has been described insome of the related applications described above and incorporated byreference. Moreover, instruments for the present spinous process implantmay facilitate percutaneous operation whether through a cannula, tube,or lumen. The instruments may include mechanisms to facilitateunfolding, opening, or deploying foldable extensions. The instrumentsmay include a draw internal or external to the spacer to pull theextensions in a direction such that the extensions are pried apart by awedge or ramp.

It has been found that presently available interspinous implants, suchas the device explained with reference to FIGS. 1-9, are good atstabilizing a spinal segment to allow it to fuse. The interspinousimplant could be implanted with less tissue trauma, however, if one ormore of the extensions could fold or pivot to allow insertionpercutaneously or through a tube, cannula or lumen. In certainembodiments, one or more of the extensions may have offset fasteners onthe foldable extension and corresponding bore into which the fastenersmay fit to allow a flat or nearly flat configuration of the folded wingfor the most compact delivery possible. The foldable extensions may foldabout an axle or be hinged to allow for movement. A draw, rod, or hookmay be connected to the hinge or axle to pull the hinge or axle towardsthe spacer that causes the face or surface of the extension to run upagainst an edge that forces the folded extension to unfold. In someembodiments, internal rods and ramps may be used to force the foldedextension to unfold or open.

Reference will now be made to FIGS. 1-9 describing an exemplaryembodiment of a spinous process implant with fixed or non-foldableextensions. One or both of the fixed, non-foldable extensions could bereplaced with the foldable extensions described further herein, but thedescription of the spinous process implant with fixed, non-foldableextensions is provided for completeness. While a specific exemplaryembodiment is provided herein, implants associated with any of theincorporated applications or similar spinous process fusion plates maybenefit from the technology of the present application to allow fixedextensions or wings to fold to facilitate implantation.

FIGS. 1 and 2 depict posterior and lateral views of a pair of adjacentvertebrae of the lumbar spine 10. A superior vertebra 12 is separatedfrom an inferior vertebra 14 by a disc 16. Each vertebra includes a pairof transverse processes 18, 19, a posteriorly projecting spinous process20, 21, and a pair of lamina 22, 23 connecting the transverse processes18, 19 to the spinous process 20, 21. In addition to the connectionthrough the disc 16, the vertebrae 12, 14 articulate at a pair of facetjoints 24.

FIGS. 1-9 illustrate an exemplary spinous process implant 100. Theimplant 100 includes a spacer 102 positioned between the spinousprocesses 20, 21. The geometry of the implant 100 is illustrated withthe use of axes that define length (l), height (h), and width (w)directions for the spacer. When implant 100 is implanted in a patient,the height direction of the spacer 102 is generally oriented along thesuperior/inferior direction of the patient's anatomy, the widthdirection of the spacer 102 is generally oriented along theanterior/posterior direction of the patient's anatomy, and the lengthdirection of the spacer 102 is generally oriented along thelateral/medial direction of the patient's anatomy.

The height 104 (FIG. 1) of spacer 102 limits how closely the spinousprocesses 20, 21 can move together. As the implant in this example is afusion plate, the height also limits how distantly the spinous processes20, 21 can move apart. Thus, the spacer 102 maintains a minimum andmaximum distance between the spinous processes 20, 21. In the case ofspine disease involving posterior subsidence of the adjacent vertebra,insertion of the spacer 102 between the spinous processes 20, 21 willmove the vertebrae apart and relieve pressure on nerve tissue and thefacet joints 24.

As shown in FIG. 3, the spacer 102 includes a first end 106, a secondend 108, and a longitudinal axis 110 extending from the first end to thesecond end. The spacer 102 has a sidewall 112, generally parallel to thelongitudinal axis 110, including superior and inferior outer surfaces114, 116. Transverse openings 118 (see also FIG. 6) communicate from thesuperior and inferior outer surfaces 114, 116 inwardly to facilitatetissue in-growth. The exemplary spacer 102 includes a hollow interior120 bounded by an inner surface 122 such that the openings 118communicate from the outer surfaces 114, 116 to the hollow interior 120.Bone growth promoting substances 124 are shown packed into the hollowinterior 120 in FIGS. 1 and 2 to promote fusion of the vertebrae 12, 14by bone growth between the spinous processes 20, 21.

The spinous process implant 100 further includes a first extension 126projecting outwardly from the spacer 102 along the spacer heightdirection h and transversely to the longitudinal axis 110 to liegenerally alongside the superior and inferior spinous processes 20, 21.Abutment of the first extension 126 with the spinous processes 20, 21helps prevent lateral movement of spacer 102, thereby maintaining spacer102 between the spinous processes 20, 21. In the exemplary spinousprocess implant 100, the first extension 126 is fixed relative to thespacer 102 and the implant includes a second extension 128 mountable tothe spacer for axial movement relative to the first extension 126. Thesecond extension 128 may be moved toward the first extension 126 toapproximate the width of the spinous processes 20, 21 and betterstabilize the implant 100. It is fixed in place by tightening a setscrew 130 (FIG. 3) against the spacer 102. The extensions 126, 128include fasteners 132, 134, 136 projecting from the extensions 126, 128to engage the spinous processes 20, 21 to fix the spacer 102 to thespinous processes 20, 21. FIG. 1 depicts an additional bone growthpromoting substance in the form of strips of bone 125 sandwiched betweenthe extensions 126, 128 along the sides of the spinous processes 20, 21to promote bone growth along the sides of the spinous processes tofurther enhance fusion of the vertebrae 12, 14. The extensions 126, 128preferably extend inferiorly as well as superiorly from spacer 102 tooptionally attach to the inferior spinous processes to immobilize thespinous processes 20, 21 relative to one another while fusion takesplace.

Fasteners 132, 134, and 136 may take any suitable form. They may be madeintegral with the extensions 126, 128 such as by machining or castingthem with the extensions or they may be formed separately andpermanently attached to the extensions 126, 128. Fastener 132 is asharpened spike that threadably engages the extension 126. The threadedengagement allows the fastener 132 to be replaced with a differentfastener 132. For example, the fastener 132 may be replaced by one thathas a different shape, a different size, a different material, or adifferent surface coating. The threaded engagement also allows thefastener 132 to be adjusted to extend by varying amounts from theextension 126 to vary how it engages the bone. Thus, the fastener 132can be adjusted to fit differently shaped bones or to penetrate into abone by varying amounts. For example, multiple threaded fasteners 132can be adjusted to extend by different amounts to conform to curved orangled bone. Finally, the threaded engagement allows the user to removethe fastener 132 when fixation is not desired such as when it is desiredto use implant 100 in a non-fusion procedure as an extension stopwithout limiting flexion.

As best seen in FIG. 3, fasteners 134 and 136 are provided asmulti-spike pods allowing a plurality of spikes to be quickly adjusted,changed, or omitted. Fastener 134 includes a non-circular tab 138engageable with a non-circular opening 140 in the extension 126. Thenon-circular engagement prevents the fastener 134 from rotating. The tab138 may form a press-fit, snap-fit, or other suitable engagement withthe opening 140. The tab 138 may be further secured by a supplementalscrew 142. Fastener 136 includes a threaded shaft 144 threadably engagedwith a base member 146 to allow the length of the fastener 136 to beadjusted. The shaft 144 engages the extension 126 in a rotating andpivoting manner such that the fastener 136 can be adjusted rotationallyand angularly to engage the bone surface. In the illustrativeembodiment, the shaft 144 terminates in a spherical ball 148 thatengages the opening 140 in a ball-and-socket arrangement for threedegrees of freedom. However, any mechanism that allows any number ofdegrees of freedom may be used. The fastener 136 may be allowed to movein use so that as the extension 126 is pressed toward a bone, thefastener 136 adjusts to the angle of the bone surface. The fastener 136also may be secured, such as by screw 142, to adjust the tension in thejoint and/or to lock the fastener 136 in a predetermined orientation.

FIG. 4 illustrates the axial relationship of fasteners on the opposingextensions 126, 128. In the illustrative implant 100, the fasteners 132at the top of the implant 100 are shown aligned along a common axis 150that is substantially perpendicular to extensions 126 and 128. Thefasteners 134 at the bottom of the implant 100 are shown offset so thatthey can interleave, if necessary, as they are pressed into a bone. Anycombination of fastener type, number, and alignment may be provided onthe implant 100.

As seen in FIGS. 5 and 6, the ends 106, 108 of the spacer 102 includeanterior chamfers 152. These chamfers 152 allow the ends 106, 108 toclear posteriorly facing structures of the vertebrae 12, 14 such as thefacet joints 24. Also, as seen in FIGS. 5 and 6, the spacer 102 isoffset anteriorly (in the spacer width direction w) relative to theextensions 126, 128 such that the longitudinal axis 110 of the spacer102 is anterior of a midline plane 154 (FIGS. 6, 8) of the extensions126, 128. The anterior offset of the spacer 102 allows it to fit deeplybetween the spinous processes 20, 21 while the extensions 126, 128 fitalongside the spinous processes 20, 21.

As best seen in FIGS. 3 and 8, the second extension 128 defines anaperture 155 conforming generally to the cross-sectional shape of thespacer 102. In the illustrative embodiment of FIGS. 1-9, the aperture155 opens anteriorly to form a “C”-shape. Tabs 156 extend inwardly fromthe superior and inferior portions of the aperture to slidingly engageelongated slots 158 in the superior and inferior surfaces of the spacer102. The second extension 128 can be translated longitudinally along thespacer length l toward and away from the first extension 126. Tighteningthe set screw 130 against the posterior side 160 of the spacer 102forces the tabs 156 posteriorly against the sides of the slots 158 andlocks the second extension 128 in place longitudinally. The posteriorside 160 of the spacer 102 may be roughened as shown to better grip theset screw 130. The set screw 130 may also dig into the surface of thespacer 102 upon tightening to positively grip the spacer 102. Theaperture 155 (FIGS. 3, 8) may conform closely to the spacer 102 toconstrain the second extension 128 to generally parallel motion relativeto the first extension 126. Alternatively, the aperture 155 may belarger than the spacer 102 by a predetermined amount to permit apredetermined amount of angular adjustment of the second extension 128relative to the first extension 126 as shown in FIG. 7 to allow theextension 128 to adjust to the underlying bone surface.

As best seen in FIG. 8, the second extension 128 includes a firstinferior lobe 161 having a first lobe centerline 162 and a secondsuperior lobe 164 having a second lobe centerline 166. In theillustrative embodiment, the first lobe centerline 162 and the secondlobe centerline 166 are parallel and spaced apart so that the secondextension 128 has a generally “Z”-shaped plan form. This shape allowsthe extension of one implant 100 to interleave, if necessary, withanother implant 100 in a multilevel surgery (as shown in FIG. 9) topermit close spacing of the implants, and/or longer extension lobes formore extensive bone engagement. In addition, first inferior lobe 161 hasa semi-circular convex shape that is generally complementary to asemi-circular superior concave surface 165 formed adjacent secondsuperior lobe 164. Similarly, second superior lobe 164 has asemi-circular convex shape that is generally complementary in shape to asemi-circular inferior concave surface 163 formed adjacent firstinferior lobe 161. As indicated in FIG. 8, first inferior lobe 161 isadjacent to inferior concave surface 163, and extension midline plane154 is located between first inferior lobe 161 and inferior concavesurface 163. Second superior lobe 164 is adjacent superior concavesurface 165, and extension midline plane 154 is located between secondsuperior lobe 164 and superior concave surface 165. Moreover, firstinferior lobe radius r₁ is substantially equal to superior concavesurface radius r₄, while second superior lobe radius r₃ is substantiallyequal to inferior concave surface radius r₂. As a result, when twoimplants are placed on adjacent spinal levels, the first inferior lobe161 of the upper implant may be (but need not be, depending on what ismedically indicated) interfitted into the superior concave surface 165of the inferior implant. In addition, the second superior lobe 164 ofthe inferior implant may be interfitted into the inferior concavesurface 163 of the superior implant. In the illustrative example ofFIGS. 1-9, first inferior lobe 161 and second superior lobe 164 form aunitary second extension 128. Although not separately depicted, firstextension 126 also has complementary lobes that are similarly configuredand oriented relative to one another.

As shown in FIG. 9, multiple spinous process implants 100 may be placedon adjacent levels of the spine. As illustrated in the figure, a firstsuperior implant 100 is positioned with its spacer 102 between a firstsuperior spinous process and a second intermediate spinous process,while a second inferior implant 100 is positioned with its spacer 102between the second intermediate spinous process and a third inferiorspinous process. The first extensions 126 of the superior and inferiorimplants are located on a first side of the patient's sagittal plane,while the second extensions 128 of the superior and inferior implantsare located on a second side of the patient's sagittal plane.

In the illustrative embodiment of FIGS. 1-9, the extension lobecenterlines 162,166 are offset equidistantly from the midline plane 154of the second extension 128. Although not separately shown, the firstextension 126 is configured similarly. The centerlines 162, 166 may varyfrom parallel and they may be offset asymmetrically to form differentshapes to accommodate different vertebral anatomy. For example, theshape may be tailored for different portions of the spine 10. In theillustrative embodiment of FIGS. 1-9, the first extension 126 has thesame shape as the second extension 128. However, the shape may be variedbetween the first and second extensions 126, 128.

As shown in FIGS. 1-9, the first extension 126 is integral or unitarywith the spacer 102 and second extension 128 has an aperture 155 that isshown to partially surround the spacer to allow the second extension 128to translate over the outer surface of the spacer 102. In certainembodiments, especially smaller implants, the aperture 155 may form athrough hole in second extension 128 to completely surround the spacer102.

FIG. 10 provides a perspective view of an exemplary implant 200. Theimplant 200 includes a spacer 202 that is sized and shaped to be fittedbetween adjacent spinous processes, such as processes 20, 21 in FIGS. 1and 2. The spacer 202 has a height h 204 extending in thecephalic/caudal direction. The height h 204 limits how closely thespinous processes can move together and functions as an extension stop.As will be explained further below, the implant 200 may be further fixedto the spinous processes such that the implant 200 also limits how farthe spinous processes can move apart such that the implant 200 is aflexion inhibitor as well, which facilitates fusion as the spinalsegments are immobilized with respect to each other. The spacer 202 hasa first end 206, a second end 208, and a longitudinal axis 210 defininga length l 212 of the spacer. The length l 212 of the spacer is in themedial/lateral direction. The length l 212 is sufficient to allow thespacer 202 to traverse an interspinous space between adjacent spinousprocesses, such as processes 20, 21. The spacer 202 is shown having ashape 214, which in this case is cubic, but other shapes are possibleincluding cylindrical, frusto-conical, or even random shapes toaccommodate patient anatomy. The spacer 202 forms an internal area 216,which will be explained further below.

The spacer 202 may include opening 218 in the cephalic and caudalsurfaces and/or the anterior and posterior surfaces. The opening 218 maybe elongated slots as shown, bores, perforations, micro pores, or thelike. The openings 218 allow for tissue or boney in-growth to formbetween the adjacent spinous processes to facilitate fusion. The spacer202 may be filled with bone growth promoting substances as describedabove.

Implant 200 includes a first extension 220 and a second extension 222.In the deployed position, both first and second extensions 220, 222extend outwardly from the longitudinal axis 210 to lie generallyalongside the superior and inferior spinous processes. Unlike implant100 described above, spacer 202, first extension 220, and secondextensions 222 may be of a modular construction as will be explainedfurther below. This provides for different sized spacers and extensionsto be mixed and matched based on the patient's anatomy or other surgicalconcerns. While modular, in this exemplary embodiment, the firstextension 220 does not traverse over the spacer 202 as does the secondextension 222. The first extension 220 when deployed may abut the firstend 206 of spacer 202. The second extension 222 is mountable to thespacer 202 at the second end 208 and may be moved toward the firstextension 220 until the surgeon is satisfied with the placement of thesecond extension 222 or the spinous processes inhibit further movement.Once placed, a locking fastener 224 is placed to lock both first andsecond extension 220, 222 in place on spacer 202.

Referring now to FIGS. 11 and 12, implant 200 is shown with the spacer202 and the first extension 220. FIG. 11 shows first extension 220 inthe unfolded position 226; whereas. FIG. 12 shows first extension 220 ina partially folded position 228. In certain embodiments, first extension220 would fold until a superior lobe 230 collapsed into the inferiorlobe 232. Alternatively superior lobe 230 and inferior lobe 232 maycollapse until engaging the outer surface of spacer 202. The superiorlobe 230 is rotationally coupled to inferior lobe 232 by a hinge joint234. While a number of hinge joints or rotational connections arepossible, in this exemplary embodiment, hinge joint 234 is formed byinferior lobe 232 having bosses 236, such as extended flanges orprotrusions, with detents or bores 238 on each of an anterior side 240and a posterior side 242 of the first extension 220. Fitting between theflanges 236 is a tab 244 coupled to the superior lobe 230. The tab 244has a bore 246 (not specifically shown) that aligns with the detents orbores 238. An axle or pin 249 extends from the detent or bore 238 on theanterior side 240, through the bore 246 to the detent or bore 238 on theposterior side 242. While not specifically shown, the hinge mayincorporate a spring, such as, for example, a torsion spring, tofacilitate folding or unfolding of the superior and inferior lobes.

The hinge joint 234 also serves as a distracter during insertion. Inparticular, the rounded or bulbous surface of the hinge joint 234 allowsfor tissue separation or distraction. The distracted tissue than travelsalong the outer surface of the superior, inferior lobes 230, 232facilitating insertion of the implant 200.

The first extension 220 has a plurality of fasteners 248 on both theanterior side 240 and the posterior side 242. The first extension 220also has a plurality of bores 250 on both the anterior side 240 and theposterior side 242. While the specific arrangement is largely a matterof design choice, strength, and function, each fastener on the anteriorside has a corresponding bore on the posterior side and each fastener onthe posterior side has a corresponding bore on the anterior side. Thus,when collapsed, the fasteners 248 align with the corresponding bore 250to allow the superior lobe to fully collapse into the inferior lobe. Ofcourse, the fasteners may be adjustable, removable, or deployable ingroups in a manner consistent with the fasteners described above. Incertain embodiments, any foldable extensions may forego fasteners tofacilitate unfolding. The bores 250 when not occupied by a fastenerprovide further fenestration of the extensions, which facilitates boneyor tissue in-growth through the extensions. The bores 250 may be packedwith bone or tissue growth promoting substances similar to the spacer202.

The first extension 220 also forms a channel 252. The channel 252 issized to fit a draw 254 that is connected to the hinged joint 234. Thedraw 254 is sized to fit within the internal area 216 and move betweenfirst and second ends 206, 208. The draw 254 may terminate in a flangedsurface 256 to inhibit removal of the draw after implantation. In thiscase, the first end 206 of spacer 202 may be swaged or pinched after thedraw if fitted to the internal area 216 to capture the draw. The draw254 may be connectable to an instrument such as, for example, a hook,via a port 270 or dimple, for example, such that the draw may be movedfrom the first end 206 towards the second end 208 to cause the superiorlobe 230 and the inferior lobe 232 to unfold. The instrument also may beused to maintain first extension 220 and spacer 202 coupled duringimplantation until locking fastener 224 may be used to lock the implant200. The posterior side 266 of the spacer 202 may include an enlargedslot 268 or window to facilitate a tool's connection to the port 270.

Each of the superior lobe 230 and inferior lobe 232 terminate at an edge258. The edges 258 may be chamfered to facilitate movement of the lobes230, 232 across a pair of bluffs 260 on spacer 202 at the first end 206.The edges may be designed to facilitate scraping tissue to facilitatemovement of the lobes 230, 232 into an unfolded position. The bluff 260also may be chamfered to facilitate movement of the lobes 230, 232across the bluffs. The first end 206 of spacer 202 may include a detent262 to accept the hinge joint 234 to allow the lobes 230, 232 to fullyextend. By moving the draw 254, the lobes 230, 232 may be deployed in arange of angles depending on patient anatomy. Generally, the lobes 230,232 will form planar surfaces, but the lobes may be arranged as requiredincluding, in some embodiments, past a planar surface such that thelobes start folding back on themselves. FIG. 11 shows lobes 230, 232forming about a 180° angle, but the lobes 230, 232 may form an angle inthe deployed condition from about 170° to about 190°.

The internal area 216 may be defined by a surface 264. The second end208 may include one or more protrusions or ratchets (not particularlyshown) radially extending from surface 264 into the internal area 216.The flanged surface 256 may engage the protrusion to provide a lock, orat least a temporary lock, for the first extension 220 until secondextension 222 is placed on spacer 202 and lock fastener 224 locks theimplant 200.

FIG. 13 shows implant 200 with first extension 220 partially deployed.As shown by FIG. 13, moving the draw in the direction shown by arrow 272causes the inner surfaces 274 of the lobes 230, 232 to move against thebluffs 260. As the inner surfaces 274 move against the bluffs 260, thelobes 230, 232 move in the direction shown by arrows 276 and unfold oropen. While not specifically shown, second extension 222 may beconstructed similar to first extension 220 to allow for folding andunfolding of the second extension as well. In this case, the draws 254may meet midline in this case. Alternatively, the draws may be arrangedsuch that one draw moves across the other.

Once implant 200 is implanted such that spacer 202 resides in theinterspinous space, and first and second extensions 220, 222 abut thespinous processes, the implant 200 is compressed such that fasteners 248fix the implant to the spinous processes. In one embodiment, a tool tocompress the implant pulls on the draw 254 and pushes on secondextension 222 causing the fasteners 248 on the first, second extensions220, 222 to clamp onto the spinous processes. Subsequent to theclamping, lock fastener 224, such as a set screw, pin, rivet, or thelike is removably connected to second extension 222 through a bore 225.The head of the lock fastener is retained in the bore 225 while theshaft of the fastener extends through the bore and the enlarged slot 268to press, pinch, or clamp the draw 254 on the anterior side of thesurface 264 defining internal area 216.

Referring now to FIG. 14, a posterior view of a spine 300 is provided.As can be appreciated, spine 300 may be divided into the cervicalvertebrae 302, the thoracic vertebrae 304, the lumbar vertebrae 306, andthe sacrum 308. Traditionally, spinous process implants, such as implant100 above, are surgically deployed by a surgeon making one or twoincisions 310 on a patient's posterior region 312. FIG. 14 shows twoincisions. For implant 100 above, the spacer 102 and first extension 126would be implanted in one of the two incisions 310 and placed in theinterspinous space with the first extension 126 on one side of theadjacent spinous processes. The second extension would be implantedthrough the other incision 310 and mated with the spacer 102 on theother side of the adjacent spinous processes. Alternatively, one midlineincision 310 may be used instead of the two slightly off midlineincisions 310 as shown. The ability of implant 200 to fold provides foran alternative implantation strategy. Instead of a midline incision toprovide access to the surgical site, which generally involvessignificant tissue trauma, a lateral or paramedian incision may be madeto provide a less traumatic approach to the surgical site. In theseapproaches, a single incision (either incision 314 or incision 316) maybe made lateral of the spine. A surgical corridor 318 may be establishedfrom the incision to the interspinous space to allow for implantation ofthe implant 200. The surgical corridor 318 may be formed by a catheter,a lumen, a tube, or the like as is generally known in the industry. In aparticular embodiment, implant 200 is used in conjunction with a lateralapproach to the spine for an interbody procedure. In a particularembodiment, a patient in need of a fusion at one or more spinal levelsundergoes a lateral surgical procedure in which a surgical corridor ismade to the desired disc space from the patient's side. For some lumbarprocedures, this may involve traversing the psoas muscle. Once theinterbody implant has been placed, implant 200 can be positioned betweenthe spinous processes at the same level. This may occur, for example, byat least partially using the same surgical corridor created for theinterbody insertion. Alternatively, a separate, laterally-orientedcorridor can be created to the interspinous space. In either case, theprocedures may be performed with minimal or no patient repositioningbeing required.

A perspective view of an implant 301 exemplary of the technology of thepresent application is shown in FIG. 15. The implant 301 has a fixedextension 303 with fasteners 305 coupled to the fixed extension 303. Thefixed extension 303 is sized to abut a first side of adjacent spinousprocesses. While described abutting a first side of the adjacent spinousprocess, bone or tissue growth promoting substances may be placedbetween the fixed extension 303 and the adjacent spinous process tofacilitate fusion, for example. The growth promoting substance may be abone sheet, an allograph or autograph washer, a plasma coating,demineralized bone matrix (DBM), bone morphogenic proteins (BMP), or thelike. Fasteners 305 are consistent with the fasteners 132, 134, and 136described above with respect to implant 100. The fixed extension 303 isshown with a superior lobe 307 and an inferior lobe 309 that aresymmetrical about a midline axis 311 of implant 301. The superior andthe inferior lobes 307, 309 may be asymmetrical to account for patientanatomy or the like. Also, the superior and the inferior lobes 307, 309may be offset in an anterior or posterior direction to facilitateinterleaving of implants 301, such as, for example, the Z-shape shown inFIG. 9. While shown as a solid plate like device, fixed extension 303may include one or more openings or fenestrations to allow for bone ortissue growth through the fixed extension 303, which would facilitatefusion.

Integral with the fixed extension 303 are a pair of cantilevered arms313, 315. In this exemplary embodiment, cantilevered arm 313 is anteriorto cantilevered arm 315. While shown as a pair of cantilevered arms, asingle cantilevered arm is possible. If a single cantilevered arm isused, the lock fastener, as described below, may be arranged to pinchthe draw to the single cantilevered arm. The cantilevered arms 313, 315have a main body portion 317 extending from the fixed extension 303. Themain body portion is of a sufficient length L 318 extending parallel tothe midline axis 311 to traverse an interspinous process gap. The mainbody portion also includes a height H 320 extending in thecephalic/caudal direction. The height H 320 limits how closely thespinous process can move together and functions as an extension stop.The cantilevered arms 313, 315 further have a tapered portion 322 thatextends from the main body portion at a location distal from the fixedextension 303. The tapered portion 322 has a decreasing height from theheight H 320 to a tip 324 of the tapered portion that forms a bulbousnose. The tapered portion 322 facilitates movement of tissue from thesurgical space during implantation and may function to facilitatedistraction of the adjacent spinous processes.

The cantilevered arms 313, 315 are spaced apart a width w 326 thatextends in an anterior/posterior direction. The space between thecantilevered arms 313, 315 forms an area 328 that is generally open toallow for a folding wing 330, to be explained further below, to foldinto and out of the area 328. The area 328 may have portions generallyproximate to the fixed extension 303 that have a superior or inferiorsurface (not specifically shown). Adding a surface spanning the area 328may facilitate adding bone or tissue growth promoting substances.

The implant 301 also comprises the folding extension 330 contained inthe tapered portion 322 of the cantilevered arms 313, 315 as shown inFIG. 15. The folding extension 330 includes a superior lobe 332 and aninferior lobe 334 that can be collapsed onto each other as shown in FIG.15 or expanded into an unfolded position as shown in FIG. 16. Thesuperior lobe 332 and the inferior lobe 334 are pivotally orrotationally connected by a hinge joint 336. A draw 338 is connected tohinge joint 336 and extends in the area 328 between the cantileveredarms 313, 315 through an aperture 340 in fixed extension 303. Moving thedraw 338 in a direction as shown by arrow 342 causes the superior andinferior lobes 332, 334 to expand or unfold.

FIG. 17 is a partial line diagram facilitating the description of thearea 328. The cantilevered arms 313, 315 have inside surfaces 350, 352opposing each other. The inside surface 350, 352 contain grooves 354,356, 358, and 360. Correspondingly, superior lobe 332 and inferior lobe334 have tongues, protrusions, or tabs 362 that sliding mate withgrooves 354, 356, 358, and 360. In the folded position, as shown in FIG.15, the tabs 362 are proximate the hinged joint 336. Grooves 354 and 356form ramps such that moving draw 338 in the direction of arrow 342causes the protrusions 362 to move along the ramps 354 and 356 forcingthe protrusions 362 to move away from each other, which causes superiorand inferior lobes 332, 334 to unfold, expand, separate, or deploy asshown. Grooves 354 and 356 communicate with essentially horizontalgrooves 358 and 360. Once opened, the protrusions 362 move from rampgrooves 354, 356 to horizontal grooves 358, 360 such that furthermovement of the draw 338 in the direction of the arrow 342 causescompression of the fixed extension 303 and the folding extension 330 toclamp or pinch the spinous processes.

With reference back to FIG. 16, the folding extension 330 is shown inthe expanded position. The folding extension 330 includes an anteriorside 363 and a posterior side 364 separated by a channel 366. Thechannel 366 is sized to fit the draw 338 when the folding extension 330is folded as shown in FIG. 15. The anterior and posterior sides 363, 364include a plurality of fasteners 368 and a plurality of bores 370. Eachfastener on the anterior side has a corresponding bore on the posteriorside, and each fastener on the posterior side has a corresponding boreon the anterior side. The fasteners 368 align with and fit into thebores 370 when the folding extension is folded to allow for a morecompact implant during implantation. When unfolded, the bores 370provide additional avenues for bone or tissue growth to facilitatefusion. Bone or tissue growth also is facilitated by area 328 beinggenerally open to allow for the superior and inferior lobes 332, 334 tounfold. To further facilitate bone or tissue growth, one or more windows372 may be provided in one or more of the cantilevered arms 313, 315.Bone or tissue growth promoting substances may be placed in window(s)372. Care should be exercised to ensure the window does not interferewith locking the extension.

Once the folding extension 330 is unfolded, and both the fixed extension303 and folding extension 330 are clamped such that fasteners 305 and368 engage the spinous processes, the implant is locked such that thefolding extension 330 does not move with respect to the fixed extension303. To accomplish this, a locking bore 374 is provided to receive alocking fastener (not specifically shown). The locking fastener isconnected to the locking bore 374 and driven such that the shaft of thelocking fastener clamps, or pinches, the draw 338 between the shaft ofthe locking fastener and one of the inside surfaces 350 or 352. Asshown, the locking bore is located in the fixed extension 303, whichfacilitates access in a lateral or paramedian access procedure, but thelocking bore 374 may be positioned at other locations, such as, forexample, in the posterior cantilevered arm 315.

FIGS. 18 to 21 demonstrate a lateral implantation of a modular implant400. Implant 400 includes a combination of the foldable extensionsexplained above with respect to implant 200 and 300, which operationswill not be re-explained herein. As shown in FIG. 18, a first portion402 of implant 400 is inserted laterally between adjacent spinousprocesses 404, 406. The first portion 402 includes a tapered or bulbouslead 408 to facilitate movement of tissue and inserting the implantbetween the processes 404, 406. Extending from the bulbous lead 408 area pair of cantilevered arms 410, 412. The cantilevered arms 410, 412form an area 414 in which a first folding extension 416 resides, ofwhich the inferior lobe 418 is shown in FIG. 18. Once the superior andinferior lobes 420, 418 are past the processes 404, 406, the firstfolding extension 416 is opened, similar to using the draws explainedabove with respect to extension 330, for example, as shown in FIG. 19.Once the first portion 402 and the first folding extension 416 areplaced, as shown in FIG. 20, the second portion 422 of implant 400 withsecond folding extension 424 is inserted. The second portion 422includes a base 426 shaped to cooperatively engage the cantilevered arms410, 412 and move along the cantilevered arms 410, 412. In thisparticular exemplary embodiment, the base 426 is a disc shape with apair of slots 428 shaped to allow the cantilevered arms 410, 412 to bereceived in the slots 428. The second folding extension 424 has superiorand inferior lobes 430, 432 that are coupled to the base 426 through ahinge joint 434 or the like. Similarly to first extension 220, thesecond folding extension 424 may have leading edges that move againstbluff surfaces to cause the superior and inferior lobes to expand. Incertain embodiments, the second portion 422 may include a driver 440coupled to a gear or the like such that rotation of the driver 440causes the superior and inferior lobes 430, 432 to open. The base 426 ismoved along the cantilevered arms 410, 412 until a desired position isreached. The device may be locked by a set screw or lock fastener asdescribed above. Alternatively, the opposed inner surfaces 444 of thecantilevered arms may have ribs 446 that form a ratchet lock withprotrusions 442 on base 426. The ratchet lock maintains the implant 400in the desired orientation with respect to the spinous processes asshown in FIG. 21.

Although examples of a spinous process implant and associatedinstruments and techniques have been described and illustrated indetail, it is to be understood that the same is intended by way ofillustration and example only and is not to be taken by way oflimitation. Accordingly, variations in and modifications to the spinousprocess implant, instruments, and technique will be apparent to those ofordinary skill in the art, and the following claims are intended tocover all such modifications and equivalents.

1.-12. (canceled)
 13. An apparatus adapted for placement in aninterspinous space between adjacent spinous processes comprising: afirst extension comprising a superior lobe and an inferior lobe, thefirst extension including an aperture, the superior lobe adapted toreside proximate a superior spinous process and the inferior lobeadapted to reside proximate an inferior spinous process; at least onearm having a first surface extending from the first extension, the atleast one arm comprising a main body portion coupled to the firstextension and a tapered portion that extends from the main body portiondistal from the first extension, the main body portion having a lengthsufficient to transverse a space between the superior and inferiorspinous process and the tapered portion terminating in a tip, the firstsurface comprising at least one groove; a foldable extension having asuperior lobe pivotally connected to an inferior lobe to allow thefoldable extension to move from a folded position to an unfoldedposition, at least one of the superior and inferior lobe comprising atleast one protrusion movably engaged in the at least one groove, and adraw having a first end and a second end opposite the first end, thedraw being connected to the foldable extension at the first end, thedraw extending through the aperture of the first extension, wherein thedraw is movable through the aperture to cause the at least oneprotrusion of the at least one of the superior lobe and the inferiorlobe to move in the at least one groove such that the superior lobe andthe inferior lobe unfold.
 14. The apparatus of claim 13, wherein thefirst extension is non-foldable.
 15. The apparatus of claim 13, furthercomprising at least a second arm having a second surface opposing thefirst surface to define a space, the second arm extending from the firstextension and comprising a main body portion coupled to the firstextension and a tapered portion that extends from the main body portiondistal from the first extension, the main body portion having a lengthsufficient to transverse a space between the superior and inferiorspinous process and the tapered portion terminating in a tip, the secondsurface comprising at least one groove.
 16. The apparatus of claim 15,wherein the at least one groove in each of the first surface and thesecond surface comprises a first groove in the tapered portion forming agenerally V shaped ramp and a second groove in the main body portionextending generally horizontal.
 17. The apparatus of claim 13, whereinthe first extension further comprises a lock bore and a lock fastener,the lock fastener engagable with the lock bore to lock the foldableextension in place with respect to the first extension.
 18. Theapparatus of claim 17, wherein the lock fastener clamps the draw betweena shaft of the lock fastener and a surface of the aperture. 19.-20.(canceled)
 21. An interspinous implant comprising: a fixed extensioncomprising: a fixed superior lobe; a fixed inferior lobe; a firstcantilevered arm extending from the fixed extension along a midlineaxis; and a second cantilevered arm extending from the fixed extensionalong the midline axis; a folding extension comprising: a foldingsuperior lobe; a folding inferior lobe; and a hinge joint coupling thefolding superior lobe and the folding inferior lobe; and a sliding taband groove coupling between the folding extension and the fixedextension.
 22. The interspinous implant of claim 21, wherein the slidingtab and groove coupling comprises: a first pair of grooves on the firstcantilevered arm; and a second pair of grooves on the secondcantilevered arm.
 23. The interspinous implant of claim 22, wherein thesliding tab and groove coupling further comprises: a first pair of tabsextending from the folding superior lobe; and a second pair of tabsextending from the folding inferior lobe; wherein the first pair of tabsand the second pair of tabs engage with the first pair of grooves andthe second pair of grooves to form a sliding connection.
 24. Theinterspinous implant of claim 23, wherein: the first pair of groovesincludes a first superior groove and a first inferior groove; and thesecond pair grooves includes a second superior groove and a secondinferior groove.
 25. The interspinous implant of claim 24, wherein: thefirst pair of tabs includes: a first tab extending from a first side ofthe folding superior lobe for riding in the first superior groove; and asecond tab extending from a second side of the folding superior lobe forriding in the second superior groove; and the second pair of tabsincludes: a third tab extending from a first side of the foldinginferior lobe for riding in the first inferior groove; and a fourth tabextending from a second side of the folding inferior lobe for riding inthe second inferior groove.
 26. The interspinous implant of claim 23,wherein the first pair of grooves and the second pair of grooves areramped.
 27. The interspinous implant of claim 26, wherein the first pairof grooves and the second pair of grooves extend away from the fixedsuperior lobe and the fixed inferior lobe in a direction parallel to themidline axis and bend inward toward the midline axis distal to the fixedsuperior lobe and the fixed inferior lobe.
 28. The interspinous implantof claim 26, further comprising a draw extending from a first end at thefolding extension proximate the hinge joint toward a second endextending through an opening in the fixed extension.
 29. Theinterspinous implant of claim 28, wherein the draw is configured to be:withdrawn from the opening to rotate the folding superior lobe and thefolding inferior lobe away from each other at the hinge joint; andpushed into the opening to rotate the folding superior lobe and thefolding inferior lobe toward each other at the hinge joint
 30. Theinterspinous implant of claim 28, wherein the folding superior lobe andthe folding inferior lobe include channels sized receive the draw. 31.An interspinous implant comprising: a fixed extension extending from afixed superior lobe to a fixed inferior lobe; a pair of opposing armsextending transversely from the fixed extension along a midline axistoward cantilevered ends, each arm of the pair of opposing armsincluding at least one groove; and a folding extension comprising afolding superior lobe and a folding inferior lobe joined at a hingejoint, wherein one of the folding superior lobe and the folding inferiorlobe includes a pair of tabs to engage the at least one groove in eacharm; wherein the at least one groove in each arm are shaped such thatthe superior folding lobe and the inferior folding lobe extend in asuperior-inferior direction when the hinge joint is proximate the fixedextension and collapse into an at least partially medial-lateralorientation when the hinge joint is pushed proximate the cantileveredends.
 32. The interspinous implant of claim 31, wherein the at least onegroove in each arm extend parallel to the midline axis proximate thefixed extension and ramp inward toward the midline proximate thecantilevered ends.
 33. The interspinous implant of claim 31, furthercomprising a draw comprising: a first end attached to the foldingextension proximate the hinge; and a second end protruding through thefixed extension.
 34. The interspinous implant of claim 33, wherein thefolding superior lobe and the folding inferior lobe each include achannel that receive the draw in the at least partially medial-lateralorientation such that the folding superior lobe and the folding inferiorlobe are capable of being recessed in between the pair of opposing arms.